Textbook Question
Under certain nonstandard conditions, oxidation by O2(g) of 1 mol of SO2(g) to SO3(g) absorbs 89.5 kJ. The enthalpy of formation of SO3(g) is –204.2 kJ under these conditions. Find the enthalpy of formation of SO2(g).
1
views
Ch.7 - Thermochemistry
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 - Matter, Measurement & Problem Solving118
- Ch.2 - Atoms & Elements106
- Ch.3 - Molecules and Compounds131
- Ch.4 - Chemical Reactions and Chemical Quantities56
- Ch.5 - Introduction to Solutions and Aqueous Solutions82
- Ch.6 - Gases114
- Ch.7 - Thermochemistry96
- Ch.8 - The Quantum-Mechanical Model of the Atom60
- Ch.9 - Periodic Properties of the Elements90
- Ch.10 - Chemical Bonding I: The Lewis Model89
- Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory85
- Ch.12 - Liquids, Solids & Intermolecular Forces51
- Ch.13 - Solids & Modern Materials47
- Ch.14 - Solutions90
- Ch.15 - Chemical Kinetics115
- Ch.16 - Chemical Equilibrium68
- Ch.17 - Acids and Bases136
- Ch.18 - Aqueous Ionic Equilibrium153
- Ch.19 - Free Energy & Thermodynamics93
- Ch.20 - Electrochemistry106
- Ch.21 - Radioactivity & Nuclear Chemistry74
- Ch.22 - Organic Chemistry140
Chapter 7, Problem 112c
Hydrogen and methanol have both been proposed as alternatives to hydrocarbon fuels. How does the energy of these fuels compare to that of octane (C8H18)?
Verified step by step guidance1
Identify the chemical reactions for the combustion of hydrogen, methanol, and octane. For example, the combustion of octane is: \[ 2 \text{C}_8\text{H}_{18} + 25 \text{O}_2 \rightarrow 16 \text{CO}_2 + 18 \text{H}_2\text{O} \]
Determine the standard enthalpy change (\( \Delta H^\circ \)) for each combustion reaction using standard enthalpies of formation from a data table. The formula is: \[ \Delta H^\circ = \sum \Delta H^\circ_f(\text{products}) - \sum \Delta H^\circ_f(\text{reactants}) \]
Calculate the energy released per mole of fuel for each reaction. This involves using the \( \Delta H^\circ \) values obtained in the previous step.
Convert the energy released per mole to energy released per gram or per liter, if necessary, to make a fair comparison between the fuels.
Compare the energy values obtained for hydrogen, methanol, and octane to determine which fuel releases more energy per unit mass or volume.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
16mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Energy Content of Fuels
The energy content of a fuel, often measured in joules or calories per gram, indicates how much energy can be released during combustion. Hydrocarbon fuels like octane have high energy densities due to their molecular structure, which allows for significant energy release when carbon-hydrogen bonds are broken. Understanding the energy content is crucial for comparing the efficiency and viability of alternative fuels like hydrogen and methanol.
Recommended video:
Guided course
01:26
Nature of Energy
Combustion Reactions
Combustion reactions involve the chemical reaction of a fuel with oxygen, producing heat, light, and combustion products such as carbon dioxide and water. The type of fuel affects the products and the amount of energy released. For instance, hydrogen combustion produces only water, while methanol and octane produce carbon dioxide, which has implications for environmental impact and energy efficiency.
Recommended video:
Guided course
02:24Combustion Apparatus
Alternative Fuels
Alternative fuels, such as hydrogen and methanol, are considered for their potential to reduce reliance on traditional fossil fuels and lower greenhouse gas emissions. Hydrogen is noted for its high energy content and clean combustion, while methanol is easier to store and transport. Evaluating these alternatives against octane involves analyzing their energy outputs, environmental effects, and practicality for widespread use.
Recommended video:
Guided course
01:19Phenyl Group
Related Practice
Textbook Question
A mixture of 2.0 mol of H2(g) and 1.0 mol of O2(g) is placed in a sealed evacuated container made of a perfect insulating material at 25 °C. The mixture is ignited with a spark and reacts to form liquid water. Determine the temperature of the water.
Textbook Question
Hydrogen and methanol have both been proposed as alternatives to hydrocarbon fuels. Which fuel contains the most energy in the least mass?
Textbook Question
Palmitic acid (C16H32O2) is a dietary fat found in beef and butter. The caloric content of palmitic acid is typical of fats in general. Which dietary substance (sugar or fat) contains more Calories per gram? The standard enthalpy of formation of palmitic acid is -208 kJ/mol and that of sucrose is -2226.1 kJ/mol. [Use H2O(l) in the balanced chemical equations because the metabolism of these compounds produces liquid water.]